New systems are being developed to purify wastewater. One popular experimental system today is the constructed, or artificial wetlands system, which runs wastewater through an aquatic environment consisting of aquatic plants such as water hyacinths, bullrushes, duckweed, lilies, and cattails (see Figure 5.14). The plants act as marsh filters, and the microbes which thrive on their roots do most of the work, breaking down nitrogen and phosphorous compounds, as well as toxic chemicals. Although they don't break down heavy metals, the plants absorb them; they can then be harvested and incinerated or landfilled.31

According to EPA officials, the emergence of constructed wetlands technology shows great potential as a cost effective alternative to wastewater treatment. The wetlands method is said to be relatively affordable, energy efficient, practical, and effective. Scientists don't yet have the data to determine with assurance the performance expectations of wetlands systems, or contaminant concentrations released by these systems into the environment. However, the treatment efficiency of properly constructed wetlands is said to compare well with conventional treatment systems.32 Unfortunately, wetlands systems don't recover the agricultural resources available in humanure.

Another system uses solar powered greenhouse-like technology to treat wastewater. This system uses hundreds of species of bacteria, fungi, protozoa, snails, plants and fish, among other things, to produce advanced levels of wastewater treatment. These Solar Aquatics systems are also experimental, but appear hopeful.33 Again, the agricultural resources of humanure are lost when using any disposal method or wastewater treatment technique instead of a humanure recycling method.

When a household humanure recycling method is used, however, and sewage is not being produced, most households will still be producing graywater. Graywater is the water that is used for washing, bathing, and laundry, and it must be dealt with in a responsible manner before draining into the environment. Most households produce sewage (blackwater). Households that produce only graywater are rare, and may even be beyond the comprehension of many government authorities who may insist that every household have a sewage system (e.g., septic system) whether they produce sewage or not. Yet, households which compost their humanure may produce no sewage at all; these households are prime candidates for alternative graywater systems. Such alternative systems are discussed in Chapter 9.